Bantam Hens?

I have two pullets that hatched out this year, one hatched in March and the other in May or June. Banjo is supposed to be a barred rock mix, but she has hardly grown! And neither has Mesha. The only small breed of chicken I have is Easter Egger, and they aren't Sylvia's offspring. Their parents are a black mixed hen and a game rooster.

These are the pullets:

And this is Mesha ( the brown hen's) mother: ( Banjo's mother was about the same size)
Could they be bantams?